我一直试图脱离示例代码并查找＆＃34; C退出功能＆＃34;在谷歌上做到这一点，但我总是在编译时遇到错误。 在我的代码中，我使用它在代码启动时将环绕声从通道1转换为2.
{
system("irsend SEND_ONCE newremote KEY_2 && gpio mode 6 output && gpio write 6 1");
}
现在我希望它能够在程序终止时将KEY_1和gpio write 6 0发送给同一个命令，以便将音频切换回主输入。
main.c: In function ‘functionA’: main.c:276:5: warning: ‘main’ is normally a non-static function [-Wmain] int main( int argc, char **argv ) ^~~~ main.c:327:1: error: expected declaration or statement at end of input } ^ At top level: main.c:276:5: warning: ‘main’ defined but not used [-Wunused-function] int main( int argc, char **argv ) ^~~~ makefile:9: recipe for target 'main.o' failed make: *** [main.o] Error 1
这是我在尝试使用示例并填写时遇到的错误。
你要求它，整个代码。 （不是我只是添加我需要的东西）
`
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <fcntl.h>
#include <unistd.h>
#include <termios.h>
#include <errno.h>
#include <pigpio.h>
#include "main.h"
#include "fft.h"
#include "draw.h"
#include "tabletop.h"
#include "serial.h"
unsigned char use_gui = FALSE;
unsigned char use_serial = TRUE;
double clip_mag = 0; // dynamic magnitude clip
double clip_mag_decay = 0; // dynamio clip decreases at rate of some function, this indexes the function
char clipped = 0; // 1 = we clipped a bin this loop
// Mag: 0.170000 Var: 0.220000
// default trigger levels for detecting beats
double MAG_TRIGGER= .82; //.36 default was .70
double VAR_TRIGGER= .82; //.36
struct bin fft_bin[FFT_NUM_BINS];
double fft_global_mag_avg;
double fft_global_mag_max;
double fft_global_hist_mag_avg; // average of all the bin history averages
double fft_global_hist_mag_max; // max value of global history
double fft_global_hist_std_avg; // avg of all the std deviations
double fft_global_hist_std_max; // max of all the std deviations
struct light lights[NUM_LIGHTS];
int i,j,k = 0;
void hsv_to_rgb( int h, int s, int v, int *r, int *g, int *b )
{
int f;
long p, q, t;
if( s == 0 )
{
*r = *g = *b = v;
return;
}
f = ((h%60)*255)/60;
h /= 60;
p = (v * (256 - s))/256;
q = (v * ( 256 - (s * f)/256 ))/256;
t = (v * ( 256 - (s * ( 256 - f ))/256))/256;
switch( h ) {
case 0:
*r = v;
*g = t;
*b = p;
break;
case 1:
*r = q;
*g = v;
*b = p;
break;
case 2:
*r = p;
*g = v;
*b = t;
break;
case 3:
*r = p;
*g = q;
*b = v;
break;
case 4:
*r = t;
*g = p;
*b = v;
break;
default:
*r = v;
*g = p;
*b = q;
break;
}
}
void init_lights(void)
{
for (i=0; i<NUM_LIGHTS; i++)
{
lights[i].state = 0;
lights[i].decay = 0;
lights[i].last_bin = -1;
}
}
void detect_beats(void)
{
for (i = 0; i < FFT_NUM_BINS; i++)
{
// shift trigger history down
for (k=1; k < HIST_SIZE; k++)
{
fft_bin[i].trigger_hist[k-1] = fft_bin[i].trigger_hist[k];
}
// see if we detect a beat
if (fft_bin[i].mag/fft_global_mag_max > MAG_TRIGGER && fft_bin[i].hist_std/fft_global_hist_std_max > VAR_TRIGGER)
fft_bin[i].triggered = 1;
else
fft_bin[i].triggered = 0;
// if this bin is decreasing from last time it is no longer a beat
//if (fft_bin_diff[i] <= 0)
// fft_bin_triggered[i] = 0;
// add current trigger state to hist buffer
fft_bin[i].trigger_hist[HIST_SIZE-1] = fft_bin[i].triggered;
}
}
void assign_lights(void)
{
int pulse_count = 0;
int center_of_pulse = 0;
// finds how many groups of pulses there are
// marks the center of them
for (i=1; i<FFT_NUM_BINS; i++)
{
// not a pulse until proved otherwise
fft_bin[i].is_pulse = 0;
// if this one is triggered and the previous one isn't we found start of group
if (fft_bin[i].triggered && !fft_bin[i-1].triggered)
{
pulse_count++;
center_of_pulse = i;
}
// if it is not triggered but the last one is we found end of group
else if (!fft_bin[i].triggered && fft_bin[i-1].triggered)
{
center_of_pulse = (i-center_of_pulse) / 2 + center_of_pulse;
fft_bin[center_of_pulse].is_pulse = 1;
}
// skip grouping logic, just count every one
//fft_bin_pulse[i] = fft_bin_triggered[i];
}
//printf("pulse_count: %d\n", pulse_count);
// go through groups of pulses and map them to lights
// a light can only trigger if either:
// 1. we find a pulse that is same place as last time for this light
// 2. the light decay is zero, meaning it has not
// had a pulse in a while so we should pulse it asap
// assume were not going to find any pulses
for (i=0; i<NUM_LIGHTS; i++) { lights[i].found_pulse = 0; }
// first find pulses that aleady have a light assigned
for (i=0; i<NUM_LIGHTS; i++)
{
for (j=0; j<FFT_NUM_BINS; j++)
{
// check if we found a pulse that is in the same spot
if (fft_bin[j].is_pulse && lights[i].last_bin == j)
{
// we found a pulse for this light
lights[i].found_pulse = 1;
// reset the decay
pulses[i].decay = LIGHT_DECAY;
lights[i].decay = LIGHT_DECAY;
// turn light on
lights[i].state = 1;
// clear this pulse since we just handled it
fft_bin[j].is_pulse = 0;
// stop looking for pulses, go to next light
break;
}
}
}
// take left over pulses and assign them to empty lights
for (i=0; i<NUM_LIGHTS; i++)
{
// loop through all the pulses
for (j=0; j<FFT_NUM_BINS; j++)
{
// check if we found an empty light
if (fft_bin[j].is_pulse && lights[i].decay == 0)
{
// we found a pulse for this light
lights[i].found_pulse = 1;
// calculate new position and color
pulses[i].x = (int)(((float)rand() * (float)(TABLETOP_WIDTH-2) / (RAND_MAX - 1.0)) + 1.0)+1;
pulses[i].y = (int)(((float)rand() * (float)(TABLETOP_HEIGHT-2) / (RAND_MAX - 1.0)) + 1.0)+1;
int color = (int)(((float)rand() * 360.0 / (RAND_MAX - 1.0)) + 1.0);
hsv_to_rgb(color, 255, 255, &pulses[i].r, &pulses[i].g, &pulses[i].b);
// reset the decay
pulses[i].decay = LIGHT_DECAY;
lights[i].decay = LIGHT_DECAY;
// turn light on
lights[i].state = 1;
// save which bin this was
lights[i].last_bin = j;
// clear this pulse since we just handled it
fft_bin[j].is_pulse = 0;
// stop looking for pulses, go to next light
break;
}
}
}
// find all the lights that did not get assigned a pulse
for (i=0; i<NUM_LIGHTS; i++)
{
// we this light has a pulse go to next one
if (lights[i].found_pulse) continue;
// turn the light off
lights[i].state = 0;
// decrement the decay for this light
if (lights[i].decay == 0)
// once the decay dies this light no long belongs to a bin
lights[i].last_bin = -1;
else
lights[i].decay -= 1;
// decrement the decay for this pulse
pulses[i].decay -= 1;
if (pulses[i].decay < 0) pulses[i].decay = 0;
// when there is a heavy bass line we want to turn on as many lights as possible
// also when there is a heavy bass line we will probably be clipping it.
// we didn't find a pulse for this light
// we clipped a bin
// this light is almost free to trigger
if (clipped && lights[i].decay < LIGHT_DECAY / 2)
lights[i].state = 1;
}
}
int main( int argc, char **argv )
{
{
system("irsend SEND_ONCE newremote KEY_2 && gpio mode 6 output && gpio write 6 1");
}
{
atexit( system("irsend SEND_ONCE newremote KEY_1 && gpio write 6 0") );
}
{
if ( use_gui )
{
printf("init_sdl()\n");
if ( init_sdl() ) return 1;
printf("init_gl()\n");
init_gl();
}
printf("init_fft()\n");
if ( init_fft() ) return 1;
if ( use_serial )
{
printf("init_serial()\n");
if ( init_serial() ) use_serial = FALSE;
}
init_lights();
init_tabletop();
while ( !done )
{
get_samples_do_fft();
detect_beats();
assign_lights();
assign_cells();
if ( use_gui )
{
if (handle_sdl_events()) return 1;
draw_all();
}
if ( use_serial ) send_serial();
usleep(5000);
}
return 0;
}
}
`
答案 0 :(得分：5)
此代码几乎肯定是语法错误：
{
atexit( system("irsend SEND_ONCE newremote KEY_1 && gpio mode 6 output && gpio write 6 0") );
}
我不确定它违反C标准的哪些部分，但它不是有效的C代码。
int atexit(void (*func)(void));
将此作为其描述的一部分：
atexit函数将func指向的函数注册到 在正常程序终止时无需参数调用。
这意味着：
void myExitFunc( void )
{
system( "irsend ..." )
}
...
atexit( myExitFunc );
...
向atexit()注册的函数不带参数，也不返回值 - 这是void (*func)(void)的含义：＆＃34;指向不带参数的函数的指针并且没有返回值＃34;。
当你在程序终止时调用atexit()来调用https://www.example.com:443/path/时，你肯定无法指定参数。
答案 1 :(得分：1)
关于：
{ system("irsend SEND_ONCE newremote KEY_2 && gpio mode 6 output && gpio write 6 1"); }
将这样的语句放在单独的函数yourexitfun中会好得多，然后main（）中的第一个语句应该是：
atexit( yourexitfun );
====================
关于：
int main( int argc, char **argv )
{
{
system("irsend SEND_ONCE newremote KEY_2 && gpio mode 6 output && gpio write 6 1");
}
{
atexit( system("irsend SEND_ONCE newremote KEY_1 && gpio write 6 0") );
}
是不正确的。建议：
// prototypes
void myexitFunction( void );
int main( int argc, char **argv )
{
atexit( myexitFunction );
system(...);
//.... rest of your code;
return 0;
}
void myexitFunction( void )
{
system( system( "irsend SEND_ONCE newremote KEY_2 && gpio mode 6 output && gpio write 6 1" );
}
答案 2 :(得分：-1)
您可以尝试使用SIGTERM并在处理函数
中运行命令 #include <signal.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
void term(int signum)
{
system("irsend SEND_ONCE newremote KEY_2 && gpio mode 6 output && gpio write 6 1);
}
int main(int argc, char *argv[])
{
struct sigaction action;
memset(&action, 0, sizeof(struct sigaction));
action.sa_handler = term;
sigaction(SIGTERM, &action, NULL);
return 0;
}